UK Approval For Efexor; Comparative Data

Wyeth-Ayerst has launched its new antidepressant agent Efexor (venlafaxine) in the UK, part of the continuing roll-out of the product into global markets. The company believes that venlafaxine has a unique activity profile, which offers improvements over older antidepressants such as tricyclic agents and the serotonin reuptake inhibitors (see also page 23).

At a press briefing to publicize the UK launch, journalists heard that venlafaxine, like some of the tricyclic agents, offers effective and balanced inhibition of both serotonergic and noradrenergic reuptake at synapses, but with very low or no activity on other receptors (eg histaminic, alpha adrenergic and muscarinic receptors) which are associated with the side effects of tricyclic therapy. And some new unpublished data presented at the meeting from a head-to-head comparison with imipramine suggests that patients on venlafaxine have a significantly lower rate of relapse at one year than imipramine-treated patients (20% versus 31%).

Venlafaxine also has theoretical advantages over the SSRIs, largely because these agents have little activity on noradrenergic reuptake, and it is now considered that transmission in both these systems should be facilitated to provide the most effective antidepressant effect. Furthermore, the drug has a demonstrated dose-response relationship (unlike the SSRIs which have a plateau response), so raising the dose may be effective in resistant disease.